Du i v , q i  ill.  hibva xy 

52 

*¥7/ 


.  -  . 


NINETEENTH  THOUSAND. 

HOW  TO  MAKE 


AT  HOME. 


By  Edward  Treyert. 


ILLUSTRATED. 


LYNN,  MASS.  : 

BUSIER  PUBLISHING  COMPANY. 
1903. 


COPYRIGHTED  1889 
BY 

LYNN  BOOK  AGENCY. 

COPYRIGHTED  1903 
BY 

BUB!  ER  PUBLISHING  CO. 


ft  'bfikh 


PREFACE 


The  design  of  this  little  volume  is  to  give  to  the 
reader  the  information  necessary  to  make  simple,  yet 
substantial  and  practical  electric  batteries,  both  closed 
and  open  circuit,  which  can  be  used  for  experimental 
purposes,  ringing  electric  bells,  operating  telegraph 
lines,  or  running  small  electric  motors,  incandescent 
lamps,  etc. 

The  necessary  articles  and  tools  required  can  be 
easily  obtained  in  any  town  or  city ;  the  expense  of 
them  being  so  small  that  anybody  may  afford  them. 

EDWARD  TREVERT. 

Lynn,  Mass.,  1890. 


By  request  of  the  publishers  I  have  added  an  ap-  ^ 
pendix  to  this  little  book,  which  I  trust  will  add  to  its 
value. 

EDWARD  TREVERT. 

Lynn,  Mass.,  1903. 


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HOW  TO  MAKE 


ELECTRIC  BATTERIES. 


Electric  Batteries  may  be  classified  accord¬ 
ing  to  their  use  into  open  circuit  and  closed  circuit 
batteries.  An  open  circuit  battery  is  a  battery 
which  is  used  when  a  current  is  needed  for  a  few 
seconds  at  a  time.  If  the  circuit  is  kept  closed  too 
long  the  battery  will  become  polarized,  that  is,  hy¬ 
drogen  will  collect  on  the  positive  plates  and  pre¬ 
vent  the  current  from  passing  through  the  circuit. 
If,  however,  the  circuit  is  opened  the  battery  will 
recover  itself  in  time.  These  batteries  are  de¬ 
signed  for  bells,  telephones,  gas-lighters,  etc. 

Closed  circuit  batteries  are  used  for  continuous 
work,  as  for  electric  lighting,  electro  plating,  fire 
alarms,  etc. 

The  simplest  electric  battery  made  is  the  Voltaic 
Cell.  This  is  made  by  placing  in  a  glass  jar  some 
water  having  a  little  sulphuric  acid  or  any  other 
oxidizing  acid  added  to  it.  Then  place  in  it  sepa- 


6 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


rately  two  clean  strips,  one  of  zinc  Z,  and  one  of 
copper  C.  This  cell  is  capable  of  supplying  a  con¬ 
tinuous  flow  of  electricity  through  a  wire  whose 
ends  are  brought  into  connection  with  the  two 
strips.  When  the  current  flows  the  zinc  strip  is 
observed  to  waste  away ;  its  consumption  in  fact 
furnishes  the  energy  required  to  drive  the  current 
through  the  cell  and  the  connecting  wire.  The 


The  Voltaic  Cell. 


cell  may,  therefore,  be  regarded  as  a  sort  of  chem¬ 
ical  furnace  in  which  the  fuel  is  zinc.  Before  the 
strips  are  connected  by  a  wire  no  appreciable  dif¬ 
ference  of  potential  between  the  copper  and  the 
zinc  will  be  observed  by  an  electrometer ;  because 
the  electrometer  only  measures  the  potential  at  a 
point  in  the  air  or  oxidizing  medium  outside  the 
zinc  or  the  copper,  not  the  potentials  of  the  metals 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


7 


themselves.  The  zinc  itself  is  at  about  1.86  volts 
lower  potential  than  the  surrounding  oxidizing 
media;  while  the  copper  is  at  only  about  .81  volts 
lower,  having  a  less  tendency  to  become  oxidized. 
There  is  then  a  latent  difference  of  potential  of 
about  1.05  volts  between  the  copper  and  the  zinc ; 
but  this  produces  no  current  as  long  as  there  is  no 
metallic  contact.  If  the  strips  are  made  to  touch, 
or  are  joined  by  a  pair  of  metal  wires,  immediately 
there  is  a  rush  of  electricity  through  the  metal 
from  the  copper  to  the  zinc,  and  a  small  portion  of 
the  zinc  is  at  the  same  time  dissolved  away  ;  the 
zinc  parting  with  its  latent  energy  as  its  atoms 
combine  with  the  acid.  This  energy  is  expended 
in  forcing  a  discharge  of  electricity  through  the 
acid  to  the  copper  strip,  and  thence  through  the 
wire  circuit  back  to  the  zinc  strip.  The  copper 
strip,  whence  the  current  starts  on  its  journey 
through  the  external  circuit,  is  called  the  positive 
pole,  and  the  zinc  strip  is  called  the  negative  pole. 

This  cell  however  is  of  little  practical  use,  it  be¬ 
ing  adapted  only  to  experimental  purposes,  as  it 
will  rapidly  polarize. 

The  bubbles  of  hydrogen  gas  liberated  at  the 
surface  of  the  copper  plate  stick  to  it  in  great 
numbers,  and  form  a  film  over  its  surface  ;  hence 
the  effective  amount  of  surface  of  the  copper  plate 
is  very  seriously  reduced  in  a  short  time.  When  a 


8 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


simple  cell,  or  battery  of  such  cells,  is  set  to  por- 
duce  a  current,  it  is  found  that  the  strength  of  the 
current  after  a  few  minutes,  or  even  seconds,  falls 
off  very  greatly,  and  may  even  be  almost  stopped. 
This  immediate  falling  off  in  the  strength  of  the 
current,  which  can  be  observed  with  any  galva 
nometer  and  a  pair  of  zinc  and  copper  plates  dip¬ 
ping  into  acid,  is  almost  entirely  due  to  the  film  of 
hydrogen  bubbles  sticking  to  the  copper  pole.  A 
battery  which  is  in  this  condition  is  said  to  be* 
"  polarized.” 


THE  LECLANCHE  CELL. 


This  cell  is  commonly  used  for  what  is  termed 
open  circuit  work — that  is  to  say,  for  work  in  which 
the  circuit  is  open  most  of  the  time  and  the  bat¬ 
tery  sends  a  current  for  a  short  time  only  between 
long  periods  of  rest.  It  has  an  internal  resistance 
of  about  3  ohms,  and  an  E.M.F.  of  1.5  volts.  It 
will  therefore  give  a  stronger  current  than  the 
gravity  cell,  but,  as  stated  above,  for  only  a  short 
time.  While  not  sending  a  current,  it  does  not  de¬ 
teriorate  as  does  the  gravity  cell,  and  it  requires 
almost  no  attention  beyond  occasionally  filling  it 
up  with  water,  and  once  in  six  months  or  so  add¬ 
ing  some  sal  ammoniac.  It  is  not  so  easily  made 
as  a  gravity  cell  but  is  more  convenient  for  many 
purposes. 

A  porous  cup  of  some  description  must  be  had 
to  hold  the  carbon  element.  It  should  be  about 
six  inches  high  and  two  or  three  in  diameter.  It 
must  be  of  unglazed  earthen  ware  in  order  that  the 
liquid  may  penetrate  it. 

Persons  who  are  near  a  pottery  can  generally 
find  something  suitable  there,  but  when  nothing 


10 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


better  can  be  had,  a  long  narrow  flower-pot  with 
the  hole  in  the  bottom  plugged  up  will  do. 

The  carbon  can  be  sawed  from  a  piece  of  “gas 
carbon/’  which  can  be  obtained  from  any  gas 
works.  It  must  not  be  confused  with  the  coke 
left  from  making  the  gas,  but  is  the  deposit  on  the 
inside  of  the  retorts  which  is  much  denser  and  finer 
grained  than  the  coke,  as  well  as  being  purer  car¬ 
bon.  A  piece  must  be  cut  out  which  will  go  easily 
inside  the  porous  cup,  and  when  touching  the  bot¬ 
tom,  project  two  inches  from  the  top.  It  should 
be  about  twice  as  wide  as  it  is  thick. 

The  top  end  of  the  carbon  should  be  paraffined 
to  prevent  the  formation  of  high  resistance  lead 
salts  between  it  and  its  cap.  This  is  done  by  dip¬ 
ping  the  end  of  the  carbon  into  melted  paraffine 
and  keeping  it  there  for  an  hour.  The  tempera¬ 
ture  of  the  paraffine  can  be  kept  right  by  putting 
the  vessel  in  which  the  paraffine  is  melted,  into 
boiling  water. 

Next  drill  two  quarter-inch  holes  through  the 
paraffine  end,  equally  distant  from  each  other  and 
the  sides  of  the  carbon,  and  three-quarters  of  an 
inch  from  the  end. 

We  shall  next  need  a  mould  for  the  leaden  cap. 
Take  a  block  of  wood  and  make  it  a  quarter  of  an 
inch  wider  and  a  quarter  of  an  inch  thicker  than 
the  carbon.  Then  take  a  strip  of  stiff  heavy  paper 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


11 


and  wrap  it  around  the  end  of  the  block  as  shown  in 
Fig  i,  the  paper  projecting  an  inch  and  a  quarter 
above  the  end  of  the  block.  First  however  a  copper 
wire  should  be  tacked  to  the  block  in  the  position 
shown,  the  end  in  the  middle  sticking  up  a  quarter 
of  an  inch,  and  the  wire  being  pressed  close  into 
the  corner  of  the  paper  where  it  comes  out  of  the 
box.  Now  pour  melted  lead  into  this  box  until  it 
is  half  full,  and  then  press  the  paraffined  end  of  the 


carbon  into  the  lead  until  it  rests  upon  the  wire  in 
the  bottom  of  the  box  and  let  it  stand  until  cool, 
when  the  paper  can  be  removed  and  the  wire  at¬ 
tached  to  the  lead  straightened  out.  The  lead  will 
run  into  the  holes  and  hold  the  cap  on  firmly,  and 
it  should  look  as  in  the  cut,  Fig  2. 

If  it  is  not  convenient  to  make  a  lead  cap,  a 
single  hole  may  be  drilled  through  the  end  of  the 
carbon  about  three-quarters  of  an  inch  from  the 


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12 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


end  and  a  round-head  wood  screw  put  through  it, 
and  screwed  into  a  wooden  block  on  the  other  side. 
The  wire  can  be  placed  under  the  head  of  the 
screw  and  so  clamped  to  the  carbon,  see  Fig  3. 

This  however  does  not  make  so  good  a  contact 
as  the  first. 

Now  break  up  some  gas  carbon  into  bits  about 
the  size  of  a  pea,  and  after  sifting  them  to  remove 


Fig.  2. 

the  dust,  take  enough  to  fill  up  around  the  carbon 
in  the  porous  cup  and  mix  with  it  about  half  as 
much  peroxide  of  manganese  in  the  needle  form, 
which  should  also  be  sifted.  Pack  the  mixture 
tightly  around  the  carbon  in  the  porous  cup. 

fn  the  commercial  form  of  this  battery  the  top  of 
the  cup  is  now  sealed  over  with  pitch,  a  hole  being 
left  for  pouring  in  water  to  start  the  battery.  A 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


13 


simpler  covering  may  be  made  of  card  board,  which 
is  cut  out  to  receive  the  carbon  rod  and  extends 
to  the  edge  of  the  porous  cup. 

For  the  zinc  element  we  will  need  a  piece  of  sheet 
zinc  as  wide  as  the  porous  cup  is  long,  and  long 
enough  so  that  when  rolled  up  in  a  cylindrical  form 
it  will  go  around  the  cup,  but  not  touch  it.  A  wire 
should  be  soldered  to  the  top  of  the  zinc. 

For  our  cell  we  shall  need  a  jar  preferably  of 
glass,  which  shall  be  large  enough  to  contain  the 
zinc  and  cup.  Put  the  zinc  inside  this  jar,  and  in¬ 
side  the  zinc  cylinder  the  porous  cup. 


tffc.  3* 

Ihe  battery  complete  is  shown  in  Fig  4. 

Now  put  in  4  oz.  of  sal  ammoniac  and  add  water 
until  the  jar  is  three-quarters  full,  and  also  pour  a 
little  into  the  porous  cup,  and  leave  the  battery  for 
three  or  four  hours,  when  it  should  be  ready  to 
give  a  current.  When  the  liquid  becomes  weak, 
and  more  sal  ammoniac  is  needed,  it  will  show  it 
by  becoming  milky  in  coloi. 

Trouble  is  sometimes  experienced  with  the  bat- 


14 


HOW  tO  MAKE  ELECTRIC  BATTERIES. 


tery  from  creeping  salts.  The  paraffine  remedy 
spoken  of  in  connection  with  the  gravity  cell  can 
be  applied  here  too. 

Another  method  is  to  avoid  the  creeping  alto¬ 
gether  by  using  a  dilution .  of  sulphuric  acid  in 
water  (i  part  acid  to  40  of  water)  in  place  of  the 
sal  ammoniac  solution. 


Fig.  4. 

A  modification  of  the  Leclanche  Cell  is  some¬ 
times  used,  which  is  said  to  have  a  higher  E.M.F., 
and  a  lower  internal  resistance.  In  place  of  the 
broken  gas  carbon  and  peroxide  of  manganese,  the 
carbon  rod  is  packed  around  with  the  so  called 
chloride  of  lime,  or  bleaching  powder,  and  the 
liquid  instead  of  being  a  solution  of  sal  ammonia^ 
is  a  solution  of  common  salt. 


THE  GRAVITY  CELL, 


For  a  person  with  limited  facilities  at  hand,  the 
Gravity  Battery  will  probably  present  the  fewest 
difficulties  in  making  and  will  be  the  most  satis¬ 
factory  for  all-around  work.  Its  internal  resist¬ 
ance  is  comparatively  high  (generally  about  8  ohms) 
and  it  has  an  electromotive  force  of  only  a  volt,  but 
it  can  be  used  as  few  others  can  for  producing  a 
steady  current  for  a  long  time,  or  in  other  words, 
is  what  is  commonly  called  a  closed  circuit  battery. 
The  elements  used  are  zinc  and  copper,  and  the 
liquids,  solutions  of  copper  sulphate  and  zinc 
sulphate. 

The  battery  may  be  cheaply  constructed  as  fol¬ 
lows  : — Procure  a  jar  the  size  you  wish  your  cell  to 
be  —  it  may  be  of  glazed  earthenware  or  glass, 
preferably  the  latter,  so  that  the  condition  of  the 
cell  may  be  seen  from  time  to  time.  It  may  be  of 
almost  any  size  but  it  will  be  well  to  have  it  some¬ 
where  near  eight  inches  high  and  six  in  diameter. 
The  size  of  the  cell  governs  the  amount  of  current 
that  may  be  obtained  from  it,  for  while  the  electro¬ 
motive  force  of  a  cell  of  any  size  is  the  same,  pro- 


16 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


viding  the  elements  are  the  same,  the  internal  re¬ 
sistance  is  increased  as  the  cell  grows  smaller, 
which  will  of  course  reduce  the  current.  So  it 
would  be  well  not  to  make  the  cell  too  small,  and  at 
the  same  time  it  should  not  be  made  very  much 
larger  than  the  dimensions  given,  since  it  would 
then  become  rather  unwieldy,  and  the  same  results, 
viz.,  the  lowering  of  the  resistance  can  be  secured 
by  using  two  or  more  cells  and  connecting  them  in 
multiple.  The  jar  should  have  a  mouth  nearly  or 
quite  as  large  as  its  body  to  facilitate  placing  the 
elements  inside  it.  Should  nothing  else  be  availa¬ 
ble,  a  large  bottle  can  be  made  to  do  by  cutting  off 
the  neck  and  upper  part. 

To  do  this,  make  a  file  mark  on  one  side  of  the 
bottle  where  you  wish  to  cut  it,  and  take  a  heated 
iron  rod,  which  has  been  previously  bent  for  a 
short  distance  to  follow  the  curve  of  the  bottle,  and 
placing  the  end  of  the  rod  at  the  file  mark  and  the 
curved  part  against  the  glass  where  you  wish  it  to 
crack,  roll  the  bottle  on  a  board  or  table.  If  it 
does  not  immediately  crack,  let  a  drop  of  water  fall 
on  the  file  mark  and  then  draw  the  iron  around  the 
bottle  when  a  crack  will  follow  it. 

The  jar  being  provided,  next  get  some  sheet 
copper  for  the  copper  element.  It  is  not  necessary 
to  have  this  very  thick  as  it  is  not  consumed  in  the 
battery.  For  the  size  jar  spoken  o*  above,  the 


SOW  TO  MAKE  ELECTRIC  BATTERIES. 


17 


copper  should  be  a  strip  two  inches  wide,  and 
may  be  rolled  up  in  the  form  of  spiral,  as  shown  in 

Fig-  5- 

A  copper  wire  should  be  soldered  or  rivetted  to 
the  copper  strip  long  enough  to  reach  outside  of 
the  jar,  and  it  should  be  insulated  to  prevent  con¬ 
tact  with  the  zinc  element.  The  zinc  element 


Fig-  5- 

should  be  heavier  than  the  copper  as  it  is  consumed 
while  the  battery  is  in  action. 

To  make  it,  lay  out  a  star-shaped  figure  on  a 
board,  by  first  drawing  a  circle  on  it,  half  an  inch 
less  in  diameter  than  the  inside  diameter  of  the 
jar.  Lay  off  the  length  of  the  radius  of  this  circle 
around  the  circumference,  and  you  will  obtain  six 
points  from  which  to  draw  lines  to  the  centre  of 
the  circle,  as  in  Fig.  6. 


18 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


With  a  round  chisel  gouge  out  grooves  along 
these  lines,  say  an  inch  wide  and  three-quarters 
dee:p,  and  you  have  a  mould  for  the  zinc  element. 
Melt  up  some  zinc  in  an  iron  ladle,  and  after  stand¬ 
ing  a  copper  wire  up  in  the  centre  of  the  mould  as 
shown  in  Fig.  7,  pour  in  the  zinc. 

When  it  is  cool  it  should  be  dipped  in  acid  to 
clean  it,  or  if  acid  is  not  at  hand  it  should  be  thor¬ 
oughly  rubbed  with  sand-paper  and  then  a  little 
mercury  rubbed  on  it  until  the  whole  surface  pre¬ 


sents  a  smooth  and  bright  appearance.  This  is 
called  amalgamation,  and  while  not  absolutely  es¬ 
sential  is  advisable  in  order  to  prevent  what  is 
called  local  action,  which  consumes  the  zinc  with¬ 
out  furnishing  any  useful  current. 

The  wire  from  the  top  of  the  zinc  can  now  be 
run  through  a  square  stick  and  bent  at  right  angles 
on  the  other  side  to  prevent  its  being  pulled  back 
by  the  weight  of  the  zinc,  and  the  zinc  is  now 
ready  for  use.  In  running  the  wire  through  the 
stick  its  length  should  be  so  adjusted  that  when 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


10 


the  stick  rests  upon  the  top  of  the  jar,  the  top  of 
the  zinc  is  an  inch  below  the  top  of  the  jar. 

Fig.  8  shows  the  elements  in  place  in  the 
jar.  An  easier  way  to  make  the  zinc  element, 
is  to  take  sheet  zinc  such  as  is  used  to  go  under 
stoves  and  cut  a  strip  an  inch  and  a  half  wide.  Its 
length  will  vary  with  the  size  of  the  jar,  and  can 
best  be  found  by  trial.  Bend  it  as  shown  in  Fig.  9, 


leaving  the  ends  long  enough  to  go  over  the 
top  of  a  stick  and  allow  the  zinc  to  hang  with 
its  top  an  inch  below  the  top  of  the  jar  when 
the  stick  is  resting  on  it.  The  ends  of  the  zinc 
should  be  screwed  to  the  stick  with  round-head 
wood  screws  and  a  wire  placed  between  the  head 
of  one  of  the  screws  and  the  zinc. 

This  style  of  zinc  element  will  give  good  results 


20 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


while  it  lasts,  but  that  will  not  be  very  long  if  the 
battery  is  used  constantly.  It  is,  however,  easily 
replaced,  and  where  the  making  of  the  other  kind 
is  not  convenient,  will  be  a  fair  substitute  for  it. 


Fig.  8. 


The  battery  is  now  ready  to  set  up.  Place  the 
copper  element  in  the  bottom  of  the  jar  and  around 
it  enough  crystals  of  copper  sulphate,  or  blue  vit¬ 
riol,  to  half  cover  it.  Then  put  in  the  zinc,  letting 
it  hang  by  its  stick  placed  across  the  top  of  the  jar. 
Fill  up  the  jar  with  water  until  the  zinc  is  covered, 
and  immediately  short  circuit  the  battery, — that  is, 
connect  the  wire  from  the  copper  to  that  from  the 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


21 


zinc.  Let  the  battery  stand  so  for  six  hours  when 
it  should  be  ready  for  use.  A  little  zinc  sulphate 
added  to  the  water  will  hasten  the  action.  The 
copper  sulphate  on  dissolving  will  give  a  blue  ap¬ 


pearance  to  the  water  in  the  lower  part  of  the  jar. 
The  condition  of  this  blue  part  is  an  index  to  the 
condition  of  the  battery.  In  a  well  kept  cell  it  will 
rise  about  half  way  between  the  copper  and 
zinc.  It  should  never  be  allowed  to  touch  the  zinc 
for  if  it  does  it  will  deposit  copper  on  it  and  this 
will  injure  the  action  of  the  cell.  If  the  blue  line 
is  getting  too  high  it  can  be  made  to  lower  by  tem¬ 
porarily  short  circuiting  the  battery.  If  it  is  too  low, 
that  is,  so  that  the  copper  shows  above  it,  more 
crystals  of  copper  sulphate  must  be  added  and  a 
little  of  the  clear  liquid  at  the  top  drawn  off  and 
water  added  to  take  its  place. 

An  annoyance  which  will  probably  be  experi- 


22 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


enced  is  from  what  is  termed  “  creeping  ”  of  the 
salts.  A  mass  of  white  crystals  will  form  about  the 
rim  of  the  jar,  and  will  spread  unless  checked, 
until  they  cover  the  outside  of  the  jar.  This  may 
be  partly  prevented  by  dipping  the  rim  of  the  jar 
in  melted  paraffine. 

The  battery  will  work  best  when  kept  constantly 
at  work.  If  left  idle  for  some  time  the  blue  and 
white  liquids  will  tend  to  diffuse  or  mix,  which  is 
detrimental  to  the  action  of  the  cell.  If  the  bat¬ 
tery  is  to  be  left  unused  for  a  long  time  it  is  best 
to  put  a  resistance  of  some  sort  between  the  ter¬ 
minals,  which  will  keep  the  battery  in  order  and  at 
the  same  time  not  use  enough  current  to  run  it 
down. 


PLUNGE  BICROMATE  BATTERY, 


One  of  the  simplest,  best,  and  most  inexpensive 
batteries  to  make  where  a  strong  current  is  wanted 
for  a  short  time  only,  is  a  Plunge  Battery.  This 
can  be  made  in  the  following  manner : 

Take  4,  6,  10,  or  any  even  number  of  common 
tumblers,  and  arrange  them  in  two  rows  parallel  to 
each  other.  The  tumblers  to  be  held  in  place  by 
an  apertured  board  supported  a  short  distance 
above  the  base-board  by  round  standards.  To 
these  fit  a  board  which  is  split  from  the  standards 
outward,  and  provide  it  with  two  bolts  with  wing 
nuts,  by  which  the  board  may  be  clamped  at  the 
desired  height.  Now  take  as  many  plates  of  carbon, 
about  1  1-2  inches  wide,  1-4  inch  thick,  and  6  inches 
long,  as  you  have  tumblers,  and  saturate  one  end 
of  them  with  a  little  melted  wax  or  paraffine  to 
keep  the  salts  from  creeping.  When  they  are  cool 
fasten  the  paraffine  ends  to  the  opposite  edges  of 
the  movable  board,  interposing  between  the  carbon 
plate  and  the  edge  of  the  board  a  copper  wire. 
The  wooden  strips  by  which  the  carbons  are  clamped 
should  be  about  one-half  of  an  inch  thick.  Take 


24 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


as  many  zinc  plates  as  you  have  carbon  plates,  tak¬ 
ing  care  to  have  them  the  same  size  as  the  carbon 
plates,  and  amalgamate  them.  This  can  be  done 
in  the  following  manner  : 

Take  a  little  diluted  sulphuric  acid  and  give  your 
zinc  plates  a  bath  in  it,  then  rub  a  little  mercury 
into  the  pores  of  the  zinc  with  a  small  tooth  brush. 
Having  done  this  the  zincs  are  ready  for  use. 

Secure  the  zinc  plates  to  the  outside  of  the 
wooden  strips  by  which  the  carbons  are  clamped. 


Fig.  io. 

This  can  be  done  by  ordinary  one-half  inch  screws, 
passing  them  through  holes  in  the  zinc  into  the 
wood.  Connect  the  copper  wire  of  one  carbon 
plate  to  the  zinc  of  the  next,  and  so  on  throughout 
the  series.  The  terminal  plates  to  be  connected 
to  two  binding  posts,  which  can  be  made  by  solder¬ 
ing  flat  pieces  of  brass  into  the  heads  of  round- 
head  wood  screws,  and  screwing  them  into  the 
wood  with  the  wire  under  the  head.  (See  Fig.  io.) 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


25 


Fill  the  tumblers  about  two-thirds  full  of  bicro- 
mate  solution.  To  make  this  solution  proceed  as 
follows : 

To  three  pints  of  cold  water  add  five  fluid  ounces 
of  sulphuric  acid.  When  this  becomes  cold  add 
six  ounces  (or  as  much  as  the  solution  will  dissolve) 
of  finely  pulverized  bicromate  of  potash.  Mix  welL 


The  Plunge  Battery  Complete. 


Always  pull  your  plates  out  of  your  solution 
when  your  battery  is  not  in  use,  as  the  zinc  is  con¬ 
tinually  being  eaten  away  when  it  is  in  the  solution. 
Each  cell  will  give  an  electro  motive  force  of  about 
2  volts. 

This  battery  can  be  used  for  running  a  small  in¬ 
candescent  lamp,  or  motor.  A  battery  of  six  cells 


26 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


will  run  a  small  five  or  six  volt  incandescent  lamp 
quite  a  little  while.  A  much  stronger  battery  can 
be  made  by  using  larger  tumblers,  or  fruit  jars  and 
proportionately  larger  zincs  and  carbons. 


THE  STORAGE  CELL. 


This  battery  has  many  advantages  over  the  pri¬ 
mary  battery.  For  places  where  a  large  current  is 
required,  such  as  for  running  lights  or  motors,  it 
can  be  used  much  more  economically  than  a  pri¬ 
mary  battery,  since  it  has  a  low  internal  resistance, 
and  in  a  well  made  battery  the  plates  should  not 
deteriorate  to  such  an  extent  that  they  have  to  be 
thrown  away  for  a  long  time.  It  is,  however,  much 
more  expensive  to  make,  and  a  good  deal  of  trouble 
to  lock  after,  and  when  one  has  not  access  to  a  di¬ 
rect  current  dynamo  of  some  sort,  it  would  be 
almost  out  of  question  to  attempt  to  do  any  thing 
with  it.  However,  supposing  the  reader  to  be  near 
some  electric  installation  where  he  can  tap  a  cur¬ 
rent,  we  will  give  him  directions  for  making  the 
battery. 

There  are  two  forms  of  storage  battery  in  use 
now,  that  with  unpasted  and  that  with  pasted 
plates.  We  will  confine  ourselves  to  the  former — 
for  while  the  latter  has  many  advantages,  such  as 
higher  E.M.F.,  greater  power  for  a  given  weight, 
etc.,  the  other  is  more  easily  made  by  a  person 


28 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


with  tew  tools,  and  is  safer  in  the  hands  of  a  be¬ 
ginner,  as  it  may  be  short  circuited  for  a  little  while 
without  damaging  it. 

A  round  glass  jar  (a  large  fruit  jar  will  do),  is 
the  first  thing  necessary.  Of  course  the  remarks 
made  before  about  the  size  of  the  battery  and 
quantity  of  current  to  be  obtained  from  it  apply 
here,  also.  Care  must  be  exercised,  however,  if 
the  cell  is  to  be  large,  to  get  it  thick  and  strong 
enough  to  stand  the  weight  of  the  lead  inside  with¬ 
out  breaking.  For  the  plates  we  shall  need  some 
strips  of  sheet  lead  about  one-sixteenth  or  three- 
thirty-seconds  of  an  inch  thick,  and  about  an 
inch  less  in  breadth  than  the  height  of  the  jar. 
The  length  of  these  strips  can  best  be  determined 
for  each  case  by  experiment.  Take  two  of  these 
strips  and  lay  them  on  a  table,  as  shown  in  Fig.  II, 


Fig.  ii. 


with  paraffined  sticks  a  quarter  of  an  inch  thici 
and  three-eighths  of  an  inch  wide,  in  the  position 
shown.  Their  number  will  depend  upon  the  size 
of  the  cell.  They  should  be  placed  about  three 
inches  apart.  The  end  stick  should  be  tacked  to 
both  top  and  bottom  plate,  care  being  taken  that 
the  tacks  do  not  go  clear  through  the  wood,  and 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


29 


touch  the  opposite  plate,  or  that  two  tacks  from  the 
opposite  sides  do  not  touch  each  other.  The  other 
sticks  should  be  tacked  to  the  top  plate  only  with 
two  tacks  to  each  stick.  Now,  beginning  at  the  right 
hand,  roll  up  the  plates  together  until  you  have  a 
roll  which  will  just  go  inside  the  jar,  and  cut  off 
what  is  left.  (See  Fig.  12.)  A  stick  should  be  placed 


Fig.  12. 


between  the  free  ends  and  tacked  to  one  of  the 
plates.  Now  unroll  your  plates,  and  if  you  are  go¬ 
ing  to  make  any  more  cells  of  the  same  size  cut 
your  lead  strips  by  these.  Take  a  coarse  file  and 
laying  it  upon  the  lead  strip,  which  in  turn  is  on  a 
soft  board,  pound  the  file  with  a  mallet,  moving  it 
about  over  the  lead  until  the  whole  surface  has  a 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


36 


roughened  appearance.  Then  turn  it  over  and  re¬ 
peat  the  treatment  on  the  other  side.  Fix  both 
plates  this  way,  and  then  roll  them  up  again,  being 
careful  that  the  plates  do  not  touch  each  other  but 
are  kept  separate  by  the  sticks,  and  put  them  in 
the  jar.  Fill  the  jar  with  a  mixture  of  equal  parts 
of  water  and  nitric  acid,  and  let  the  lead  plates 
stand  in  it  for  a  day,  when  they  should  be  removed 
and  thoroughly  washed. 

This  treatment  gives  the  surface  of  the  lead  a 
porous  or  roughened  appearance,  and  thus  increases 
the  surface  which  may  be  acted  upon  by  the  cur¬ 
rent.  Now  turn  out  the  nitric  acid,  and  place  in 
the  bottom  of  the  cell  a  stick  a  quarter  of  an  inch 
square,  which  has  been  boiled  in  paraffine.  This 
stick  is  to  keep  the  lead  from  the  bottom  of  the 
cell,  and  thus  prevent  short  circuiting  from  the  fine 
powder  which  may  fall  from  the  plates.  Solder  a 
wire  to  the  top  of  each  of  the  lead  plates,  and  put 
the  plates  on  the  stick,  and  fill  the  jar  with  diluted 
sulphuric  acid  (i  part  acid  to  io  of  water)  which 
has  been  mixed  four  or  five  hours  previously. 

In  mixing  the  acid,  care  must  be  taken  or  it  may 
fly  up  and  go  over  the  face  or  clothes. v  "The  acid 
should  be  poured  in  a  fine  stream  into  the  water. 

Your  battery  is  now  ready  to  charge.  The 
method  of  doing  this  will  vary  with  the  circum¬ 
stances.  If  you  have  a  large  number  of  batteries, 


MOW  TO  MAKE  ELECTRIC  BATTERIES. 


3l 


say  45,  and  a  constant  potential  dynamo  supplying 
current  at  iio  volts,  the  cells  may  be  connected 
up  in  series,  and  placed  directly  between  the  mains. 
When  first  starting  up,  or  when  reversing  the 
cells,  it  would  be  well  to  have  a  resistance  of  say 
20  ohms  in  series  with  the  cells  which  can  be  cut 
out  when  the  cells  have  become  formed  sufficiently 
to  oppose  the  current  with  their  normal  voltage. 
This  can  be  seen  when  one  set  of  plates  turn  a 
chocolate  color. 


The  Storage  Cell  Complete. 


Should  you  have  a  fewer  number  of  cells,  and  the 
Iio  volt  circuit  at  command,  insert  a  resistance  in 
series  with  the  battery,  which  will  cut  down  the 


32 


nOW  TO  -VIAKE  ELECTRIC  BATTERIES. 


charging  current  to  about  5  amperes  for  the  fruit 
jar  size  cell. 

When  the  number  of  your  cells  is  small,  charg¬ 
ing  from  a  constant  potential  circuit  of  no  volts 
becomes  very  wasteful,  on  account  of  the  large 
amount  of  energy  used  up  on  the  resistance. 
Under  such  circumstances  if  an  arc  current  is 
available,  it  would  be  well  to  use  that,  and  in  fact 
it  could  be  used  to  advantage  with  a  large  number 
as  well  as  a  small  number  of  cells. 

If  it  is  a  current  of  from  5  to  7  amperes,  your 
cells  may  be  connected  in  series  with  each  other 
and  the  circuit. 

If  a  larger  current,  say  of  10  amperes  is  used, 
then  the  cells  should  be  connected  by  twos  in 
multiple,  and  the  twos  in  series  in  such  a  way  that 
each  cell  will  receive  about  5  amperes. 

If  you  only  have  one  cell  and  a  10  ampere  cur¬ 
rent,  shunt  the  cell  with  a  resistance  of  about  half 
an  ohm  and  connect  the  terminals  into  the  circuit. 

We  are  supposing  the  most  probable  cases  where 
a  person  lives  near  a  lighting  station  or  installation. 
Any  dynamo  that  can  pass  a  current  of  from  5  to 
10  amperes  through  the  cells  may  be  used, 
but  as  there  are  so  many  ways  in  which  this  can 
be  done,  no  specific  directions  can  be  given  that 
will  fit  each  case.  A  smaller  current  may  be  used, 
and  this  is  one  of  the  beauties  of  this  cell.  It  can 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


33 


be  charged  with  a  small  current  for  a  proportion¬ 
ally  longer  time,  and  then  give  out  a  large  current, 
for  a  short  time. 

Having  decided  upon  the  best  means  of  charg¬ 
ing  our  cell  we  begin  by  passing  a  current  through 
it  in  one  direction  for  from  20  to  30  hours — not 
necessarily  continuously,  but  preferably  so.  If  the 
cells  begin  to  boil  violently  after  a  short  time,  the 
current  should  be  reduced,  not  that  boiling  hurts 
the  cell,  but  it  wastes  energy.  Moderate  boiling  is 
not  harmful,  and  is  an  indication  that  the  cell  is 
working  well. 

After  charging  for  the  specified  time,  let  the 
cell  rest  for  five  or  six  hours  and  then  discharge  it 
through  a  resistance  that  will  allow  5  or  10  amperes 
to  pass,  and  as  soon  as  the  cell  is  discharged  begin 
to  charge  in  the  opposite  direction,  and  let  it  go  on 
for  the  same  length  of  time  as  before,  after  which, 
let  the  cell  rest  again  and  then  discharge.  Charge 
again  in  the  opposite  direction  and  repeat  the 
operations  given  above  until  the  cell  has  been 
discharged  four  times,  when  it  should  be  “formed.” 
Now  charge  again  for  five  or  six  hours  in  the  same 
direction  that  it  was  last  charged  and  the  battery 
is  ready  for  business. 

Each  cell  should  give  about  2  volts  a  littk  above 
this  at  first,  and  a  little  under  towai  Jta  che  end  of 
the  discharge.  It  should  never  be  allowed  to  dis- 


34 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


charge  after  the  E.M.F.  has  dropped  to  1.8  volts 
per  cell.  It  should  never  be  allowed  to  stand  dis¬ 
charged.  After  using  it  for  awhile,  charge  up 
again,  and  if  the  cells  are  to  stand  idle  for  a  long 
while  they  should  be  charged  every  month,  to  com¬ 
pensate  for  the  losses  from  leakage. 

When  a  cell  is  charged  it  is  shown  by  the  liquid 
boiling  briskly.  The  current  passed  through  it 
after  that  is  nearly  all  wasted  but  a  little  more  may 
be  forced  in  by  stopping  the  charging  current  for 
a  while  and  starting  up  with  the  current  dimin¬ 
ished.  After  the  cell  has  once  been  formed  the 
charging  should  always  be  done  in  the  same  di¬ 
rection. 

If  the  cell  has  been  left  discharged  for  some 
time,  or  the  acid  solution  becomes  too  weak,  the 
positive  or  chocolate  colored  plates  will  “  sulphate,” 
or  turn  a  grayish  color.  This  may  be  remedied  by 
overcharging  the  battery,  which  means  to  continue 
to  pass  a  current  through  it  after  it  has  commenced 
to  boil.  This  should  be  done  until  the  last  trace 
of  the  sulphate  has  disappeared. 

The  battery  will  lose  a  great  deal  of  its  liquid  by 
evaporation  and  decomposition,  and  should  be  filled 
up  with  water  as  soon  as  its  level  gets  much  below 
that  of  the  top  of  the  plates. 


PRICES  OF  ARTICLES  REQUIRED 

In  the  Manufacture  of  the  Batteries  Described 
in  This  Book. 


Blue  Vitriol  (Sulphate  of  Copper),  per  pound,  ioc. 


Bi-chromate  of  Potash,  “  “  25  c. 

Sulphate  of  Zinc,  “  “  ioc. 

Sulphuric  Acid,  “  “  ioc. 

Pure  Granulated  Sal  Ammoniac,  “  “  20c. 


(Eight  cents  worth  being  enough  for  an  ordinary  cell.) 


Peroxide  of  Manganese,  per  pound,  1 5c. 

Mercury,  “  “  $1.00 

Sulphuric  Acid,  “  “  20c. 


Any  of  these  articles  can  be  procured  at  a 
drug  store  or  an  electrical  supply  store. 


GLOSSARY  OF  ELECTRICAL  TERMS. 


ACCUMULATOR. — See  battery  and  condenser. 

AMMETER. — An  instrument  for  measuring  cur¬ 
rent  strength. 

AMPERE. — The  unit  of  current  strength.  It  is 
the  flow  of  electricity  produced  by  the  pressure 
of  one  voh  a  resistance  of  one  ohm. 

ARC. — The  stream  of  hot  gasses  and  particles  of 
carbon  visible  between  the  carbons  of  an  arc 
lamp. 

ARMATURE. — That  part  of  a  dynamo  in  which 
the  current  is  induced.  It  may  be  a  stationary 
or  moving  part,  but  is  generally  the  latter,  and 
is  composed  of  coils  of  wire  which  “cut”  the  lines 
of  magnetic  force  produced  by  the  fields.  This 
“cutting”  induces  a  current  in  the  coils. 

BATTERY. — One  or  more  cells  in  which  electric¬ 
ity  is  produced  by  chemical  action.  There  are 
two  elements  of  different  substances  and  a  liquid 
in  every  voltaic  battery.  A  primary  battery  is 
one  in  which  the  “elements”  are  placed  and  used 
until  they  are  worn  out.  In  a  secondary  orstor- 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


37 


age  battery  or  accumulator  the  “elements”  are 
placed  in  the  cell  and  first  “formed”  by  the  pas¬ 
sage  of  a  current  of  electricity  through  them. 
The  cell  is  then  said  to  be  charged  and  may  be 
used  to  supply  electricity.  The  term  battery  is 
also  used  to  designate  a  collection  of  Leyden 
Jars  in  which  static  electricity  is  stored. 

BRUSH. — A  collection  of  metal  sheets  or  wires 
which  press  against  the  commutator  of  a  dy¬ 
namo  to  collect  the  electricity,  or  of  a  motor  to 
supply  it.  Carbon  brushes  are  coming  into  use 
now,  especially  in  railway  work. 

B.  &  S. — Brown  &  Sharp.  The  wire  gauge  used 
in  America. 

B.  W.  G. — Birmingham  wire  gauge.  The  English 
wire  gauge. 

CELL. — The  jar  in  which  the  elements  and  liquid 
of  a  battery  are  placed.  The  term  is  used  also 
for  the  jar  and  its  contents. 

C.  G.  S. — The  abbreviation  of  centimetre,  gramme, 
second,  and  used  to  designate  the  so-called  ab 
solute  system  of  measurements. 

CIRCUIT. — A  system  of  conductors  over  which 
electricity  passes. 


38 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


COIL,  CLOSED. — The  coils  of  an  armature  are 
said  to  be  closed  when  the  end  of  one  is  connect¬ 
ed  to  the  beginning  of  the  next  at  the  com¬ 
mutator  bar.  An  open  coil  armature  is  one  in 
which  each  coil  is  independent  of  the  others  and 
has  its  own  commutator  bars. 

COMMUTATOR. — That  part  of  a  dynamo  on 
which  the  current  from  the  armature  is  rectified 
before  passing  to  the  external  circuit.  The  cur¬ 
rent  in  a  given  section  of  an  armature  alternates 
and  must  be  made  continuous  on  leaving  it. 
This  is  done  by  the  commutator,  which  consists 
of  a  series  of  insulated  metal  bars  connected  to 
the  armature  wires,  and  so  placed  as  to  feed  into 
different  brushes  as  the  current  changes. 

CONDENSER. — An  apparatus  for  collecting  and 
holding  electricity.  It  consists  of  alternate  lay¬ 
ers  of  conducting  sheets  and  insulating  material, 
the  conductors  being  very  close  together,  and 
the  adjacent  ones  being  charged  with  the  oppo¬ 
site  kinds  of  electricity.  Their  proximity  en¬ 
ables  them  to  hold  a  larger  amount  of  electricity 
than  they  could  if  alone.  Condensers  are  some¬ 
times  called  accumulators. 

CONDUCTOR. — A  substance  which  will  allow 
the  passage  of  electricity  over  it.  All  substances 
will  do  this,  but  some  to  so  small  an  extent  that 
they  are  called  insulators. 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


39 


COULOMB. — The  unit  of  electric  quantity.  It  is 
the  amount  of  electricity  which  flows  past  a  giv¬ 
en  point  in  one  second  on  a  circuit  conveying 
one  ampere. 

CURRENT. — The  flow  of  electricity  in  a  conduct¬ 
or  analagous  to  the  flow  of  water  in  a  pipe. 
A  continuous  current  is  one  that  does  not  change 
its  direction,  while  an  alternating  current  is  one 
that  periodically  reverses. 

CUT  OUT. — An  arrangement  for  interrupting  a 
current  or  for  shunting  it  around  some  part  of  a 
circuit. 

DYNAMO. — A  machine  driven  by  power  which 
furnishes  electricity. 

DYNAMOMETER. — An  apparatus  for  measur¬ 
ing  the  power  given  out  or  consumed  by  a  ma¬ 
chine.  An  electro-dynamometer  is  an  instru¬ 
ment  for  measuring  a  current  by  the  mutual  ac¬ 
tion  of  two  coils  through  which  it  passes. 

ELECTRODE. — A  pole  of  a  battery. 

E.  M.  F. — An  abbreviation  for  electro-motive 
force.  This  is  the  pressure  which  forces  the 
electric  current  through  a  conductor. 

ELECTRO-MAGNET. — A  magnet  produced  by 
passing  a  current  through  a  coil  of  wire  around 
a  soft  iron  core.  The  core  is  magnetized  while 


40 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


the  current  flows,  but  loses  its  magnetism  when 
the  current  stops.  This  form  of  magnet  may  be 
made  much  more  powerful  than  a  permanent 
magnet,  and  is  therefore  used  in  place  of  the  lat¬ 
ter  in  dynamos. 

FARAD. — The  unit  of  capacity.  A  condenser 
that  will  hold  one  coulomb  at  a  pressure  of  one 
volt  has  a  capacity  of  one  farad. 

FILAMENT. — In  an  incandescent  lamp  the 
thread  of  carbon  which  becomes  luminous  when 
the  current  is  passed  through  it. 

GALVANOMETER.  An  instrument  for  detect¬ 
ing  and  measuring  the  electric  current  by  the 
iction  of  a  coil  of  wire  upon  a  magnetic  needle. 

INDUCTION. — A  current  is  said  to  be  induced 
in  a  conductor  when  it  is  caused  by  the  conduct¬ 
or  cutting  lines  of  magnetic  force.  A  fluctuaL 
ing  current  in  a  conductor  will  tend  to  induce  a 
fluctuating  current  in  another  running  parallel 
to  it.  A  static  charge  of  electricity  is  induced 
in  neighboring  bodies  by  the  presence  of  an  elec¬ 
trified  body.  A  magnet  “induces”  magnetism  in 
neighboring  magnetic  bodies. 

INDUCTION  COIL. — An  arrangement  by  which 
an  alternating  or  fluctuating  current  in  a  coil  cf 
wire  will  induce  an  alternating  current  in  a  para] 
lei  coil. 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


41 


INSULATOR. — The  opposite  of  a  conductor.  A 
body  which  will  not  allow  the  passage  of  electric¬ 
ity  except  in  such  small  quantities  as  to  be  negli- 
gable. 

LINES  OF  FORCE. — Imaginary  lines  which  radi¬ 
ate  from  a  magnet  and  show  by  their  direction 
the  path  which  a  free  magnetic  pole  would  take 
if  left  to  itself.  Conventionally,  the  strength  of 
of  a  magnetic  field  is  indicated  by  the  number  of 
these  lines.  Their  form  is  shown  by  the  well- 
known  experiment  with  the  magnet  and  iron 
filings. 

MAGNET. — A  body  possessing  the  property  of 
attracting  iron,  steel  and  a  few  other  metals. 

MAGNETIC  FIELD. — The  space  around  a  mag¬ 
net  in  which  its  power  of  attraction  is  exhibited. 

MULTIPLE  or  MULTIPLE  ARC.  A  method 
of  connecting  electric  conductors  by  which  a 
number  of  sources  of  electricity  feed  directly 
into  or  a  number  of  receivers  of  electricity  take 
it  directly  from  the  same  mains. 

NEGATIVE. — A  conventions1  term  to  indicate  the 
direction  of  flow  of  a  current,  or  the  state  of  elec¬ 
trification  of  a  body.  The  negative  or  terminal 
of  a  dynamo  is  the  one  at  which  electricity  en¬ 
ters  it  from  the  external  circuit,  while  the  nega¬ 
tive  terminal  of  a  lamp  or  instrument  is  that  con¬ 
nected  towards  the  negative  terminal  of  a 
dynamo.  It  is  designated  by  — 


42 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


OHM. — The  unit  of  electrical  resistance. 

OHMS  LAW. — States  that  the  current  in  any 
circuit  is  equal  to  the  E.  M.  F.  acting  on  it 
divided  by  its  resistance. 

PERMANENT  MAGNET.— A  piece  of  hardened 
steel  which  retains  its  magnetism  after  the 
magnetizing  influence  is  removed. 

PARALLEL. — See  Multiple. 

POLE. — Those  parts  of  a  magnet  which  show  the 
strongest  magnetic  force.  In  a  bar  magnet  this 
is  generally  a  short  distance  from  the  ends.  The 
pole  of  a  dynamo  or  battery  is  one  of  its  termi¬ 
nals. 

POSITIVE. — A  conventional  term  to  show  the 
direction  of  a  current.  In  a  dynamo  or  battery 
it  is  the  terminal  at  which  the  electricity  leaves 
it.  It  is  designated  by  +. 

POTENTIAL. — Power  to  do  work.  It  is  com¬ 
monly  used  as  synonymous  with  electro-motive 
force  in  speaking  of  dynamos  or  batteries. 

RESISTANCE. — The  opposition  offered  by  a 
body  to  the  passage  of  electricity  through  it. 

RHEOSTAT. — An  apparatus  for  throwing  avail¬ 
able  resistance  into  a  circuit  at  will. 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


4a 


SERIES. — Two  or  more  conductors  are  said  to  be 
in  series  when  they  are  so  connected  that  the 
same  current  that  passes  through  one  passes 
through  the  other. 

SHORT  CIRCUIT. — An  indefinite  term  used 
generally  in  the  case  of  dynamos  and  batteries 
for  a  resistance  between  the  terminals  lower 
than  the  machine  or  battery  is  calculated  to  stand 
or  run  on  in  practice.  With  lamps  the  term  is 
used  for  a  low  resistance  between  the  terminals, 
which  deprives  it  of  the  most  of  the  current. 

SHUNT. — A  shunt  is  a  conductor  connected 
around  another  in  such  a  way  that  it  deprives 
the  first  of  a  part  of  the  current. 

SOLENOID. — A  hollow  coil  of  wire. 

TERMINAL. — The  point  at  which  the  electricity 
enters  or  leaves  an  electrical  apparatus. 

VOLT. — The  unit  of  electro-motive  force  or  pres¬ 
sure  analogous  to  the  head  of  water  in  hydraul¬ 
ics. 

VOLTMETER. — An  instrument  for  measuring 
the  voltage  or  pressure  on  a  circuit. 

WATT. — The  unit  of  work.  The  watts  developed 
in  a  circuit  are  equal  to  the  current  multiplied  by 
the  E.  M.  F.  746  watts  equal  one  horse  power. 

WATTMETER. — An  instrument  for  measuring 
the  electrical  energy  in  a  circuit. 


APPENDIX 


HOW  TO  MAKE  A  HOMEMADE 
ELECTRIC  BATTERY, 


Following  are  given  directions  for  making  a 
good  and  efficient  Bichromate  Cell.  Take  a  fruit 
jar  that  will  hold  about  a  quart,  and  to  this  fit  a 
wooden  cover  made  of  about  one-inch  board.  Take 
two  carbon  plates  about  six  inches  long,  one  and 
one-half  inches  wide  and  one-quarter  inch  thick,  and 
dip  one  end  of  them  into  melted  paraffine  wax  to 
keep  the  salts  from  creeping.  When  they  are  cool, 
fasten  the  paraffine  ends  into  the  wooden  cover.  This 
may  be  done  by  cutting  two  holes  about  one  and  one- 
half  inches  apart,  one  for  each  carbon  plate,  so  that 
they  will  fit  tightly.  The  carbons  should  be  con¬ 
nected  together  by  a  piece  of  copper  wire  inserted 
between  them  and  the  wood.  Now  bore  a  hole  in 
the  centre  of  the  wooden  cover,  between  the  carbon 
plates,  for  the  zinc.  A  common  Leclanche  zinc  rod 
will  be  good  enough  for  the  negative  element,  but 


HOW  TO  MAKE  ELECTRIC  BATTERIES. 


45 


it  should  be  amalgamated.  This  may  be  done  in 
the  following  manner.  Take  a  little  sulphuric  acid 
and  give  the  zinc  rod  a  bath  in  it,  then  rub  a  little 
mercury  into  the  zinc  with  a  tooth-brush,  when  it 
will  be  ready  to  use.  Now  screw  a  binding-post 
through  the  wooden  cover  into  the  top  of  one  of  the 
carbon  plates,  and  your  battery  is  complete. 


HOW  TO  MAKE  A  DRY 
BATTERY. 


The  cell  is  contained  in  a  sheet  zinc  (all  one 
piece)  jar  about  two  and  one-half  inches  diameter 
and  eight  inches  deep,  the  metal  being  about  one- 
sixteenth  inch  in  thickness.  A  carbon  plate  five- 
sixteenths  of  an  inch  thick,  one  inch  wide  and  six 
inches  long,  forms  the  positive  electrode.  The 
space  between  the  carbon  and  zinc  is  filled  with  a 
paste  of  the  following  composition  :  —  Oxide  of 
zinc,  i  part,  sal-ammoniac,  i  part,  water,  2  parts,  all 
by  weight.  Do  not  let  the  carbon  touch  the  zinc, 
either  on  the  sides  or  bottom  of  the  cylinder.  The 
unoccupied  space  at  the  top  may  be  filled  with  a 
mixture  of  melted  beeswax  and  resin  in  equal  parts. 
This  will  seal  it  and  keep  it  air-tight.  The  electro¬ 
motive  force  is  about  1.3  volts.  For  convenience  a 
pasteboard  box  may  be  made  just  large  enough  to 
set  the  battery  cell  in,  and  cover  it  to  the  top  of  the 
zinc  cylinder. 


ZINC  FOR  BATTERIES.* 


As  it  is  considerable  trouble  for  an  amateur  to 
cast  a  zinc  plate  for  his  experimental  battery,  and 
as  an  amalgamated  one  of  sheet  zinc,  without  being 
supported  in  some  way,  is  too  brittle  to  stand  hand¬ 
ling,  the  writer  has  found  that  a  good  zinc  plate  can 
be  made  easily  and  cheaply  by  placing  an  amalga¬ 
mated  piece  of  sheet  zinc  between  glass  plates  of 
the  same  size,  and  holding  the  plates  in  place  by 
rubber  bands. 

A  short  conducting  wire  should  be  soldered  to 
the  zinc  before  it  is  amalgamated.  —  Bichromate 
cells  for  students’  work,  with  zincs  one  inch  by  six 
inches,  made  in  this  way,  were  very  satisfactory  in¬ 
deed,  and  the  zincs  lasted  a  long  time. 

*  Thos.  R.  Baker  in  Bubier’s  Popular  Electrician. 


HOW  TO  MAKE  A  CHLORIDE 
OF  SILVER  BATTERY. 


A  Chloride  of  Silver  Battery  is  very  small,  and 
owing  to  its  expense  is  used  for  testing  purposes 
and  to  run  small  medical  batteries. 

It  is  usually  about  two  and  one-quarter  inches 
long  and  one  inch  in  diameter. 

The  voltage  is  i.i,  but  the  internal  resistance 
being  8  ohms,  its  current  output  is  very  meagre. 
Procure  a  glass  vial  or  test  tube  of  the  above 
dimensions. 

Through  a  suitable  cork  stopper  press  a  rod  of 
amalgamated  pure  zinc,  about  one-quarter  inch  di¬ 
ameter  and  three  inches  long. 

The  chloride  of  silver  is  to  be  cast  in  the  form  of 
a  cylinder  about  one-quarter  inch  diameter  and  one 
and  one-half  inches  long,  with  a  silver  wire  in  its 
centre  for  connection,  and  wrapped  in  a  piece  of  fine 
parchment  paper.  The  silver  wire  passes  through 
the  cork  and  is  to  be  soldered  to  the  zinc  of  the 
next  cell. 


THE  PROPORTION  OFCARBON 
TO  ZINC  IN  A  BATTERY. 


The  amount  of  current  obtainable  from  a  battery 
depends  largely  on  its  internal  resistance,  that  is 
the  resistance  offered  by  the  liquid.  The  more 
carbons  there  are  the  less  the  resistance  will  be. 

After  determining  the  amount  of  zinc  that  it  is 
cared  to  use,  put  in  as  many  carbons  as  to  make 
four  or  five  times  as  much  carbon  as  zinc  surface. 


RULE  FOR  OBTAINING  THE 
EFFICIENCY  OF  A  BATTERY. 


To  find  the  efficiency  of  a  battery,  divide  the  re¬ 
sistance  of  the  external  circuit  by  the  resistance  of 
the  external  circuit  plus  the  internal  resistance  of 
the  battery,  and  multiply  by  ioo. 

Letting  Eff  =  Efficiency,  we  have 


Eff  = 


R 

R+r 


X  ioo 


What  is  the  efficiency  of  a  battery  of  50  cells,  the 
external  resistance  of  the  circuit  being  20  ohms, 
the  internal  resistance  of  each  cell  being  .2  ohms  ? 
Solution  :  Applying  the  foregoing  rule  we  have  : 


E£f  =  wir  x  100 

R+r 

„  .  20  X  100 

Rquals - 

30 


20  X  100 
—  20  +  (50  X  .2) 

=  66^  per  cent. 


HOW  SHOULD  PRIMARY  BAT¬ 
TERIES  BE  CONNECTED  WITH 
STORAGE  BATTERIES  FOR 
CHARGING? 


Imagine  a  storage  cell  nearly  discharged ;  it  ex¬ 
erts  a  certain  push  or  electromotive  force  from  its 
positive  pole. 

The  charging  battery  must  encounter  and  over¬ 
come  this  electromotive  force  and  implant  a  charge 
in  the  opposite  direction.  Hence  the  carbon  of  the 
primary  (if  gravity  cells  are  used  the  copper)  is  to 
be  connected  to  the  positive  of  the  storage  cells. 
We  do  not  think  it  advisable  to  use  anything  but 
glass  for  jars  of  gravity  batteries.  The  successful 
working  of  these  cells  is  dependent  upon  keeping 
the  line  between  the  white  and  blue  solutions  half¬ 
way  between  zino*and  copper.  This  condition  can¬ 
not  be  discernible  unless  the  containing  vessel  is 
transparent. 


